My continuing CDROM2 problems

[soop]

I filmed a video.  Although the sound didn't come out, it should give an indication of what's wrong.

The disc never spins apart from the occasional shunt, and this is after I replaced the laser.  Does this point to something in particular?

[BlueBMW]

Typically when I see them just kind of flick the disc but never really spin it up, its usually an adjustment issue.  I'll shoot you a PM with some more info.

[thesteve]

if the spindle is pushed down it will have problems focusing.

[soop]

if the spindle is pushed down it will have problems focusing.

Ah, I forgot to add here - after I adjusted the potentiometers according to the diagram Blue kindly provided, the drive will now light up in PC mode and never switch off.  So it looks like it's getting somewhere.

I see - Might I have screwed the cover plate on too tight? I think that's the only way it could be pushed down more than necessary.   Although it is actually missing one of the 2 screws.  Also, the I can spin the CD ok with my finger, and it won't stop immediately after I close the lid

[soop]

Bumpety bump!

Right,  while ago, I messed around with the potentiometers, and I managed to get the drive to spin up for about 5-10 seconds or so.  Spins up really fast (in PC and Audio modes), but then cuts out.

Thought I was getting somewhere, but all this week, I've only managed to make everything worse, and then today gotten back to that state.

the pots are being modified by pure guesswork (rather than specific readings), but even so...  anyone knows why it won't load?  (It never gets past the Super CD screen)

[BlueBMW]

You say it was spinning really fast, like it was about to take off and fly kind of fast?

[soop]

Not quite, not as fast as a modern cd drive, but faster than before.  How come?

Just checked;  roughly 6 revs per second, 360ish per minute.

[thesteve]

if the disk is spinning too fast it means its not tracking/reading.
the speed is controlled be a data buffer.
when the buffer is low it spins faster to read faster

[soop]

if the disk is spinning too fast it means its not tracking/reading.
the speed is controlled be a data buffer.
when the buffer is low it spins faster to read faster

I don't think it's spinning obscenely fast... Blue said in a PM that it might not be finding the table of contents, but I can't find any info on that.  Where's the buffer?  I have 2 different Super CD cards (though I can't actually test them, since the only other CD drive I have is a Super CD ROM) and the same thing happens with both. I could also try a different core unit, but this one plays games fine, so I doubt it's that.

[incrediblehark]

its probably too late for this, since you most likely tweaked all of the pots, but I found that only adjusting VR101 had the most success for me in getting my cdrom2 to work, i think i adjusted vr103 as well, but it was 101 that seemed to have the most impact on getting my discs to play.

[soop]

its probably too late for this, since you most likely tweaked all of the pots, but I found that only adjusting VR101 had the most success for me in getting my cdrom2 to work, i think i adjusted vr103 as well, but it was 101 that seemed to have the most impact on getting my discs to play.

I don't know which is which off the top of my head, but the leftmost (the one on it's own) has the greatest to do with the disc spinning up or not.  Then the two white ones (right-most) seem to have the most to do with the laser focus.  But this is all conjecture really on my part.

[thesteve]

the data buffer is in the drive itself.
if its spinning up its finding the TOC.
sequence
1 lens bobs up and down looking for its reflection.
2 reflection seen, lens resets to center of disk and disk spins to read TOC.
3 system reads TOC and tells drive which track to read.
4 lens moves from center towered edge counting tracks.
5 track found, data reading.
6 spindle speed adjusted as needed to keep data buffer memory full.

[soop]

I have managed to make it do this (interestingly, it likes doing it with music cds) but I think buffering is not the problem

I think the problem is finding the toc.  It never goes above 0 on a music cd.

[thesteve]

the TOC is what determines if its a music cd.
i suspect its getting a partial read of the TOC

[Charlie]

Got a VOM?
Start with these voltages:
VR101 = 2.0V
VR104 VR102 = (see below)
VR103 = 2.5V
VR104 = 2.5V
VR105 = 3.5V

For VR104VR102, set it to 2.25V, then adjust the other pots slightly to see if you can get reliable results.  If not, increase VR104VR102  to 2.30V, repeat pot adjustments.  If not, increase VR104VR102 to 2.35V, etc....upto VR104VR102  = 2.65V.

Note that all voltages above are not "set in stone", all the values will vary slightly, including VR104VR102  start voltage and end voltage.

Most important...the results of a pot change may NOT be immediate, so after each change, wait a few seconds for the circuit to settle in.


Charlie

Edit 6/6